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Character set division into "digits"
- To: GLS at MIT-MC
- Subject: Character set division into "digits"
- From: JONL at MIT-MC (Jon L White)
- Date: Tue, 23 Sep 80 18:10:00 GMT
- Cc: (BUG LISP) at MIT-MC, NIL at MIT-MC
- Original-date: 23 SEP 1980 1410-EDT
Date: 22 September 1980 1525-EDT (Monday)
From: Guy.Steele at CMU-10A
To: bug-lisp at MIT-MC
Message-Id: <22Sep80 152518 GS70@CMU-10A>
. . .
[I have been considering changing CHPROP so that DIGITP would take
an optional argument (default 10.) specifying the radix. Are there
any objections to this
I've argued for a reader-independent notion of DIGITP, returning the digit's
"weight" as you suggest, so that a *character set* standard can be proffered.
Whether or not that predicate for "digitability" is called DIGITP is not much
concern to me, but I would like to point out that that has been the definition
in NIL;NEWFUN > for almost two years; furthermore, I'd sure hate to see that
two-line, reader-useful function
(DEFMACRO BASE-DIGITP (D &optional (B 10.) &aux (VAL (GENSYM)))
`(LET ((,VAL (DIGITP ,D)))
(AND ,VAL (< ,VAL ,B) ,VAL)
fully displace the current DIGITP and thus wipe out all semblance of
program-independence in the character standard.